Reaction Rates and Equilibrium

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2 Rates of ReactionEssential Question: How is the rate of a chemical change expressed, and what four factors influence the rate of a chemical reaction?

3 Reaction RatesThe speed of chemical reactions can vary from instantaneous to extremely slow.A rate is a measure of the speed of any change per interval time.Reaction rate = amount of reactant changing per unit time.

4 Collision Theory Particles react when they collide with one another.The collision must have sufficient kinetic energy to break existing bonds.This minimum energy is called activation energy.

6 Energy DiagramsActivation Energy – minimum energy that colliding particles must have in order to react.Activated Complex – unstable arrangement of atoms that forms momentarilyTransition State – synonym for the activated complex

23 Solubility EquilibriumEssential QuestionWhat does the solubility product constant tell you about the solubility of a compound, and how can you predict whether a precipitate will form when salt solutions are mixed?

26 Common Ion EffectLowering the solubility of an ionic compound as a result of the addition of a common ionIf the product of the concentrations of two ions in the mixture is greater than Ksp of the compound formed from the ions, a precipitate will form.

27 Entropy and Free EnergyEssential QuestionWhat two factors determine the spontaneity of a reaction, and what are the characteristics of spontaneous reactions?

28 Spontaneous ReactionsOccur naturally and favor the formation of productsProduce substantial amounts of products at equilibrium

29 Nonspontaneous ReactionsDoes not favor the formation of productsDo not produce substantial amounts of products at equilibriumNote: Speed is NOT a factor

30 Entropy Changes A measure of the disorder of a systemLaw of Disorder: the natural tendency is for systems to move in the direction of maximum disorder or randomnessAn increase in entropy favors spontaneous chemical reactions